This proposal requests renewal of support for a postdoctoral training program, now in its 28th year, at the NCI designated Basic Cancer Center of the Salk Institute for Biological Studies. This program provides advanced training in research to postdoctoral scientists pursuing careers in basic and translational research related to cancer. Major activities include molecular, cell and developmental biology research within the three Cancer Center Programs: Metabolism and Cancer, Mouse Models and Cancer Stem Cells, and Growth Control and Genomic Stability. The Cancer Center occupies 73,000 sq. ft. of laboratory space and includes 32 faculty members, 22 of whom are members of the training faculty. Currently there are 187 postdoctoral and 58 predoctoral trainees in the Cancer Center. Trainees devote 100% of their time to research. Trainees in the program also participate in a variety of special activities designed to enhance their knowledge of cancer biology and therapeutic applications of basic research. These include the Cancer Biology Course, Cancer Forum and Cancer Center Symposium. These activities are designed to significantly augment the cancer relevance and focus of the individual laboratory training experience. We request funding to continue to support six trainees. The trainees will hold Ph.D. and/or M.D. degrees, and will be chosen on the basis of the quality and cancer relevance of research proposals they submit. The average duration of training will be three years, as at present. Upon completion of training the trainees will be fully qualified to conduct independent research in molecular and cellular biology related to cancer.